The Mendelmax 3 & Fusematic from Makers Tool Works are built in the USA and sourced from US suppliers. The guy behind it has done more for the RepRap mechanical bits, aside from Joeseph Prusa.

The Lulzbot mentioned below was based on the Mendelmax 1.5. This line of printers moved RepRap from a threaded rod construction to extruded aluminum. Also the first to have linear rails instead of steel rod+linear bearings. The new Mendelmax3 is a mix of laser cut parts and extrusions - and has required less service than any of my printers to date.

LulzBot might be of interest to you. Best power-user printers on the market IMHO, and made in Indiana.